


Dirty Little Surprise

by amamiya_toki



Series: 輝く、僕と私の日々 [3]
Category: IDOLiSH7 (Video Game)
Genre: Alternate Universe - Canon Divergence, Drunkenness, Established Relationship, F/M, Genderswap, Lingerie, Masturbation, Nipple Play, Power Play, Vaginal Fingering, Voyeurism, Webcam/Video Chat Sex
Language: English
Status: In-Progress
Published: 2017-12-04
Updated: 2017-12-07
Packaged: 2019-02-10 13:01:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,499
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12912456
Author URL: https://archiveofourown.org/users/amamiya_toki/pseuds/amamiya_toki
Summary: When Tenn is unable to return on time from his job in another part of the country, Riku could not help but feel upset as she longs to see him. Learning about this, her friend Nagi suggests that she should surprise him with an unexpected treat. As embarrassing as it may be, she is willing to go through with it as it is for his sake.





	1. Part 1

**Author's Note:**

  * Inspired by [Diamond Days](https://archiveofourown.org/works/11469678) by [amamiya_toki](https://archiveofourown.org/users/amamiya_toki/pseuds/amamiya_toki). 



> I came up with this idea yesterday after waking up from my afternoon nap, buzzed Nezu-san about it and wrote this part in one sitting in the late evening.
> 
> I'm changing the POV mid-story at certain parts, hence why it's in separate parts. Was supposed to be just two but my inspiration took a different approach than planned.
> 
> I hope the entire story will be completed by Christmas, hopefully, since I'm been working overtime a lot recently. It may be even out before that, since I don't have anything planned for the rest of the year.

"I'm just so, so sorry, Riku."

"Don't be, Tenn-nii. No one expected something like that to happen."

"But you were so looking forward to our date… since it's our special anniversary. You know I'd hate to see you sad or make you disappointed. I'll make it up to you when I get back. I promise."

"Goodness, I said it's fine already. Your work is more important, after all, and it's something that no one expected to happen. It's not your fault and you're not to blame."

"Riku, you know that there's nothing more important in my life than you."

Nanase Tenn could only sigh about the situation he was thrown into.

It had been a more than two and a half years since he graduated from volitional school. Before his graduation, he had secured a job at a production company as a junior producer. Although he had some qualms about getting in through his connections, namely his senior and mentor from volitional school. As his job required him to work both in the office and out at studios and recordings, it was certainly not easy. However, he was able to adapt well and proved to be a capable worker, earning the respect and approval of his colleagues and superiors.

Few are aware that Tenn—who was popular with the ladies—has a girlfriend and lover. However, only those who are close to them know that his partner was his younger twin sister, Nanase Riku who writes novels under an alias. The two began their relationship in middle school, despite the concerns and worries that he initially had as well as their falling out after high school.

Initially, he was living on his own in a dingy little apartment and she was still living with their parents. After a year and half of working full-time, he was finally able to afford better lodgings and moved to a bigger apartment that was closer to his office. When he did, he invited her to live him with him. It was an offer she gladly accepted. She worked from home, so she had no reason to refuse. Their mother, who was well aware of the true nature of their relationship, gave them her permission and blessings.

At the present time, Tenn was out of the prefecture for work, supervising a movie project with his senior producer. He was due to return home the next day but was unable to do so due to bad weather and a series of unfortunate events. Because of this, his return was delayed by at least two days.

He had called her to inform her of this and to apologise as their planned date on the day after his return had been ruined. What made him feel worse was that he knew how much she was looking forward to it.

"Speaking of which, you're headed out tomorrow?"

"Yeah! Nagi invited me out on a shopping trip. We're also going to have afternoon tea and dinner together."

"With the kid or without?"

Izumi, formerly Rokuya, Nagi was the beautiful half-Japanese wife of Izumi Mitsuki, whose family were close friends with their own. The two got married about four years ago, a month before Tenn and Riku turned twenty. They had their first child, a boy, in the summer the year after. Mitsuki worked in his family's business, a patisserie and cafe, while Nagi was a fashion model.

"Without. It's going to be just the two of us."

"But isn't she expecting another one?"

"She's only about three months along, so she's still good to move around. Oh, I just heard from Mitsuki-san that she even got an offer to model for maternity clothing when the baby bump gets bigger."

"Wow."

"I know, right?"

"Nagi-san aside, how is your new novel going?"

"There hasn't been much progress. I'm stuck on the progression of the main pair's relationship. Maybe going out with Nagi tomorrow will be a good change of pace."

"I hope it will. Ah, it's getting late and we're having an early morning tomorrow, so I'm going to end the call to sleep soon. It's going to be a long day since we're trying to wrap everything up so I'll let you know when's good to call."

"I was thinking of sleeping early too. Good night, Tenn-nii. Have a good rest."

"I will. Good night, Riku. Sweet dreams. I love you."

"I love you too, Tenn-nii."

Riku blew him a kiss before taking the initiative to end the video call. She placed her smartphone down on the bedside table after that, plugging the cable in to let the device charge. Leaning backwards and sinking further into the bed, she let out a small sigh as well. She did tell Tenn that she was fine with the sudden but inevitable change of plans, but she could not help but feel disappointed.

What made her feel down, however, was not because the date was cancelled. Rather, it was because she had been looking forward to spending time with him after his week-long absence. She could not help but feel lonely without him around, despite having friends to talk to. She missed him but did not dare to tell him as she did not want to interfere with his work.

This feeling lingered on to the next day, something which her friend picked up. Fortunately, the blonde woman offered her more than a listening ear.

"All you have to do is surprise him! Knock his socks off!"

Riku initially had no idea what she had meant by that, but it did not sound like a bad idea. She should have asked what Nagi had in mind, specifically, because she had some regret agreeing without finding out what she had agreed to. She was unable to back down from the plan, knowing how tenacious her friend was, so she decided to go along with it.

Truthfully, it was not a bad idea. It's not something that is completely unheard of, nor was it unusual or weird. However, for someone like her to do something so… so bold, it would certainly take loads of courage.

She could feel the heat of embarrassment on her face when Nagi dragged her into the shop, which did not dissipate after she left clutching the discrete paper bag against her chest. In fact, she could still feel the burn on her cheeks when she stepped into the apartment. She glad she ate a little less than usual during dinner, as the anxiety was making her stomach feel uncomfortable.

She dropped her bag and other items in the living room, intending to take a bath before anything else, but took with her the neatly wrapped package from the brown bag with her.

She set it on the counter next to the sink, to be unwrapped after she was done with her bath. Her heart was pounding fast as she washed off the dirt and grime of the day before immersing into the tub of heated water. However, the very thought of the package was still enough to make her stomach flip.

"It's all for Tenn-nii," she convinced herself, in hopes to ease the anxiety she was feeling.

After drying off, it was finally time to face the music.

With trembling fingers, she slowly unwrapped the waxed paper and picked up the flimsy garment carefully.

In her opinion, what she was holding could barely be called a piece of clothing. What she had purchased was a black babydoll and panty set, something that she had not bought before in her 24 years of life. Nagi had chosen it for her since she was unable to make up her mind.

Taking a deep breath to steel her nerves, she slipped it over her head to try it on.

The bralette was made of lace, the cups framing her ample cleavage just nicely. While the lace was patterned with roses, did not change the fact that it was completely see-through. From below the breasts, the cascade of sheer extended down, stopping just below her plump butt-cheeks. It was held up on the shoulders by spaghetti straps that were so thin that she was afraid that they would break.

That panty that came with the gown did no better in doing its job as a piece of clothing. Rather than what she usually wears, this was nothing but strings and a small piece of cloth at the front, made from the same see-through material as the top.

Never once did she think that she would have to wear the infamous G-string, or so she thought as she tried to brush aside as she slipped it on.

In the package, however, was one more item that she did not recall being made to choose: a pair of sheer thigh high socks, also in black with a lace trim. Nagi must have slipped these in with the lingerie set, if she had to guess. She had already put on the two revealing pieces, so the socks were probably nothing at this point in time.

Thinking about it, having to wear the entire lingerie set was probably nowhere as embarrassing as what the blonde had suggested she do while wearing it.

After she was done, she glanced at herself in the mirror. It was then that it occurred to her: What would Tenn think if he saw her wearing something like this?

Would he tease her?

Would he think bad of her, that she was immodest?

Perhaps, would he think that something like this did not suit her? He was always treating her like a child, or so she felt, so she wonders if he actually considers her a woman at times.

However, in her own eyes, she could barely believe that the person staring straight at her in the mirror was she herself.

This is the first time that she ever thought of her own body as that of an adult's. Perhaps this was because this was the first time that she actually looked at her own body properly in the mirror. Perhaps the one who actually thought of her as a child was not Tenn, but herself. Because of this, the sight of her womanly figure—from the curves of her hips and posterior to the fullness of her breasts—was more surprising than it should be.

However, she could not say with confidence that she is beautiful. The only person who ever made her feel that way was the love of her life, the man who she has chosen to spend her life with.

If so, she would leave for him to decide, how she looked in this... well, outfit.

Despite that, it was strange.

He sent her a message around the time that she finished dinner that the last of work had wrapped up and the entire crew was going out for dinner to celebrate, along with the time that he intended to return to his hotel room. However, it was half an hour past that time and he had not informed her of his return or any other updates.

Could something have happened?

She was tempted to call to check, but she stopped herself from doing so. He was probably busy, so it would not be wise to interrupt him.

Well, she does have some time to spare now, as she had nothing to do for the rest of the evening. Maybe she could get ready, and maybe a little 'practice' in while waiting for him to contact her...

**\- to be continued -**


	2. Part 2

**Notes for the Chapter:**

> I said I'd finish this by this part but I ended up wanting to switch to Riku's point of view again hence the need for part 3. I've changed the rating and tags since I set the direction for the story with this update. Not sure if I missed any (tags) but let me know if I did.
> 
> Only reason why this was out so fast was because I happened to suffer food poisoning and wasn't able to leave the house, so I was stuck on my smartphone the whole day.
> 
> Enjoy!

Nanase Tenn was never fond of social gatherings and parties, even if it was for work.

He knew the significance and importance of such events. He was also aware that having to attend them was inevitable. However, he had no interest in such merry-making and only would stay for a little while, for the sake of formality, only to escape soon after.

This time, he was unable to.

This was not the first time he had been dragged to an after-recording party. I was part of the job, as their company president had informed him once before. However, he seemed to be unable to find a way to slip away from the cheer and excitement of the group. From what he had heard, there would be more than one party tonight. At the moment, he was stuck at the one organised for both cast and crew. The latter would be going out for their own after-party later in the evening. This made his senior, who had proudly introduced himself as Gouda "no alcohol no life" Yukimitsu on his first day of work, thrilled.

Tenn did not like alcohol (neither did Riku, by the way) but he was, by no means, a lightweight. However, endless refills seemed to have found their way into his glass this evening, served to him by eager young maidens who hoped they would have a chance with him.

Poor things. They do not know that his heart had already been someone else's a long time ago.

Amongst the buzz of chit-chatter and flurry of activity, Tenn lost track of how many glasses he was made to down. However, he could feel that it was beginning to get to his head. That was a sure sign that he had far too much to drink.

"Yo, Nanase, you okay?"

"I'd like to say I am, but no, I'm not."

"Well, you may have had too much to drink tonight. Here, have some water."

The burly man offered him a glass, which he accepted with both hands. "Thanks, Gouda-senpai."

"No problems at all!" The jolly man laughed. "But really, it's tough being popular with the ladies, yeah? Then again, that's youth for you!"

"Senpai, you aren't all that old yourself."

"Naw, the moment you hit thirty, you're an old man in the eyes of young'uns."

Tenn held back the temptation to roll his eyes as he downed the glass of water. "I think I'll be going back to the room first. I'm not feeling too good."

"Need me to bring you up to the room?"

"No, I'll be fine."

"Are you sure? You look pretty drunk to me. What if you get cornered by a hot babe on the way up, get hypnotized by her soft mounds and before you know it, spirited away to her room and a passionate one night-long wonderla—"

"Senpai, I believe you're taking your teasing a little too far. And I'm not drunk."

Tenn stood up from the floor cushion he had been sitting on, and as he did he scowled at the man. His senior, knowing that he had offended him, spouted a quick apology. It was common knowledge in the office how dedicated this young man was to his beloved, so his joke was definitely in bad taste.

"Ehh? Nanase-kun, you're leaving already?"

"Stay with us, the night is still young!"

The young ladies who had been trying to chat him up noticed him before he could take his leave and tried to stop him. Tenn felt a twinge of annoyance at their persistence and self-centered behaviour, but as an adult, he knew better than to kill the mood and cause unnecessary trouble.

"I'm sorry, but I haven't been feeling too well today." It was a practised lie that rolled smoothly off his tongue. "I'd like to rest, so I'll be taking my leave now."

"Oh! Sorry!" They did not seem apologetic, but it seems that they are letting him go. "Have a good rest!"

He quietly slipped out of the room after that, ignoring the persistent throbbing of his head as he walked down the hallway towards the elevators. There were few people around aside from the employees, so it was much quieter compared to the dining hall they had reserved. That helped to ease the discomfort he was feeling.

"I'll never drink this much again, or with Gouda-senpai again," he swore under his breath as he leaned against the wall of the elevator as it rose up to the instructed floor.

It stopped with a 'ping' before the doors opened.

Tenn's room, which he shared with his senior, was located in the middle of the hallway. He found the door easily despite the dimmed lighting. Fishing the key card from his pocket, he tapped it on the reader. There was a small clicking sound from the unlocking of the door, and he entered the room.

One of the beds in the twin room was littered with clothes and other small items. This was his senior's bed, which was closer to the window. The mess was probably left there after the shower he took before dinner. Tenn's own was against the wall and was kept neat and tidy.

Exhausted, he slipped off his jacket and plopped face down on the soft white sheets.

He should take a bath, or at least a quick shower before bed. They were leaving first thing after breakfast the next morning, and he had intended to pack before his senior returned to the room. The older man had announced that he would be going drinking the entire night with the rest of the men and would probably only be back in the dead of the night, if not the next morning. That left him with plenty of time, but the alcohol was had drained him of his motivation to do anything.

When Riku's name came to mind, he felt the need to call her and tell her how much he missed her.

He was pondering where he had left his phone when he felt it buzz in the back pocket of his jeans. He reached behind and fished it out to check on the notification, which informed him that his dear sister had sent him an image via the Rabbit Chat app, which they used for both messages and calls.

He swiped the notification to view the attachment, which prompted him for his 4-digit passcode. He keyed in the string of numbers, 7458, without haste and the application started up, directing him straight to the message thread.

The image took a little longer than usual to load, as they were in a rural area where telecommunications infrastructure was not as abundant as in the city.

However, what he saw left him at a complete loss for words, and probably made his blood run south.

Riku sending him selfies was nothing new. In actuality, it was very common, especially when she was out at gatherings or trips with friends or other authors. When he saw the notification, he thought he may have taken one with Nagi during their ladies' day out.

That was why when the image showed her, alone in a seductive pose, he had to do a double take to make sure that what he was seeing was not an illusion.

The picture had been taken from a high angle, so it did not provide a complete view of the lingerie she wore. However, the almost-transparent black material was a strong contrast to her fair, creamy skin. This seemed to emphasise certain parts of her body, including her cleavage and the slenderness of her shoulders. For a few moments, he could not take his eyes of the peaks of her breast, as he could almost see her nipples through the lace. She even had one hand (the one that was not holding her phone) placed on her flat abdomen, raising the curtain of sheer to expose the little pucker of her belly button.

Tenn would be lying if he said that he was not turned on. In the first place, he never thought he would see Riku wear something like this with his own two eyes.

It was shameful to admit this but he had fantasied about her, more often than one thought he would, in such raunchy attire. There were times when he passed by lingerie shops at a mall thinking how adorable she would look decked in lace, sheer and satin.

However, this was reality, and it far surpassed each and every one of his fantasies.

It was also much different from his expectations. To him, Riku had always been nothing but adorable. She wore nothing but bright-coloured clothes and always dressed in a way that still makes people mistake her for a teenager. Aside from denim, she avoided dark colours completely.

This was the first time he had seen her wear something that made her seem so... so adult-like. Even the costumes that she had helped his senior's girlfriend back in volitional school could not compare to this. It was not because it was revealing... it barely hid anything, like the naked apron she attempted for their 22nd birthday, and her naked body was something he had seen since he was a child. However, there was something about this that was completely different from anything he had seen before.

If this was her trying to seduce him, which is nothing new, he would declare this her best and most successful attempt thus far. And for the record, the alcohol he had consumed earlier had nothing to do with this.

Or so he convinced himself.

Without thinking, he had tapped on the button to initiate a voice call via the application as he sat up on the bed, stretching his legs out. It was picked up within two rings.

"Te-Tenn-nii?" Her breathing seemed a little unsteady, but she sounded rather scared as she called out his name.

"Riku... what was that about?"

"That...?"

"That picture."

"That..." She squeaked out, in the manner that she always would whenever he confronted her about something she wanted to keep from him.

"You're wearing it now, aren't you?"

"N-No..." She stammered but was unable to lie to him as he was using the deep tone that usually appeared when he gets extremely angry. However, she was unaware that Tenn was not furious but was instead attempting to contain himself. "Yes... I am..."

"Let me see you."

"Eh?"

"I'm going to switch to video mode now. Let me see you properly."

He could have gone ahead to do that without informing her. However, knowing how shy she was, she would have rejected the video call out of embarrassment.

Starting the video call, she was holding the phone at her usual position: only her face and neck can be seen. He noted the fierce blush that dusted across her cheeks which he had interpreted as adding on to the erotic ensemble.

"Put your phone down on the bed and prop it up with a pillow. I want to see everything." He had intended it as a request, but it sounded closer to a command. "Spread your legs. Good, raise them higher."

He continued giving specific orders until her body was visible to his gaze.

Riku had both hands holding up the skirt of sheer, exposing everything below the lace that covered the mounds of her chest, even more than the image she had sent him several minutes ago. Her legs were raised high and spread open, and that allowed him to see everything between them. At that angle, the G-string could not do anything to hide her sensitive folds, instead, the thin black stripe served as a guide to tell Tenn where he should set his gaze upon.

"Te-Tenn-nii, this is embarrassing."

"You say cute things like that, but you actually have an ulterior motive. Don't you, you naughty girl?"

As he spoke, he watched her body clench up. He had long known how Riku was weak to dirty talk, and he loved watching how his words affected her. This is why he cannot stop teasing her, no matter how often she protests about it.

"Tell me, Riku. Why did you decide to buy something like this?"

"Y-You don't like it? Are you angry?"

"Don't reply to my question with your own."

"I-It wasn't me! Nagi was the one..."

"You could have said no or refuse. Yet you still went along with that woman's whims. So tell me, what were your true intentions?"

"I... I only thought that doing something like this would make you happy, that's all! I'm doing this for you, Tenn-nii!"

"What were your thoughts when you were putting this on?"

"It was very embarrassing, but I was hoping that you would think of me as a woman... beautiful. sexy and gorgeous."

If this was in a normal situation, Tenn would offer words of support in reply. He knew that Riku, as bold as she always was, often felt insecure in matters related to their relationship. However, whenever he was drunk (but would claim that he was not), his kind, gentle self would fail to surface. Instead, he would be cold and mildly sadistic. He would remember everything he said and does after he sobers up and would regret his actions. Unfortunately for him, Riku seems to like him when he is in that state.

This fact, however, mattered little at that moment.

He was tempted to push her down on their bed and make love to her until morning comes. It was the only thought that was on his mind, aside from the awareness of the discomfort building up in his groin. It was getting more unbearable, desiring and demanding release from its confinement.

Tenn kept his eyes fixed on the screen of his phone, he slowly undid his belt with his free hand. As he did, he decided to provide her with his next round of instructions. "Riku."

"Y-Yes!"

"You said you are doing this for me, didn't you?"

"I did..."

"Then show me what you really mean by that."

Riku did not seem to understand what he was implying, responding to his demand with a confused expression. At this time, Tenn got his belt free and continued working on the fastenings of his black jeans.

"I want you to please yourself. Touch and caress yourself all over: your breasts, nipples, the smooth skin of your belly... even your most intimate areas. Show me how you want me to touch you, make love to you, while you are in that get-up looking like a slut begging to be fucked and milked."

Now that she knew exactly what he wanted she could only blush, more profusely than she had been before. "But… I don't know how to…"

It was the truth; since they were always together, she had always depended on him to satisfy her sexual needs.

"Do you want me to teach you?" She did not pause event for a moment before nodding as if she had been expecting him to offer.

Tenn's lips curved into a smirk, relishing in the fact that he had control over her.

Now with his pants and briefs removed, his erection was exposed to the cold air of the room. He leaned against the wall for comfort, stroking the organ lightly.

"Are you ready?"

"A-Anytime you are, Tenn-nii."

A chuckle, unusually low for his regular pitch, escaped his lips. "Good girl. That's my Riku."

**\- to be continued -**

**Notes for the Chapter:**

> If I didn't mention, this series will have OCs, just that they haven't made their debut yet.

**Author's Note:**

> The lingerie set I referenced for Riku can be found on Amazon JP (you'd be surprised that you can find almost anything there) and I'll leave the link for those who are curious: <http://amzn.asia/1DdQIf5>.
> 
> I should just come up with a series to collate the parts of this AU together since I'm already coming up with so many extra and side stories when the sequel to Diamond Days is only in the planning stage (not even plotting). I just need a name. Which, I don't have.


End file.
